Power turbine system

ABSTRACT

The power turbine system includes two power turbines communicating with an ion transport membrane (ITM) reactor. Heavy liquid fuel is atomized and burned within the reactor to drive the first turbine, with the first turbine producing useful power. Exhaust from the first turbine is recycled back into the reactor. The reactor includes a series of concentric cylindrical ion transport membranes that separate atmospheric and exhaust gases into suitable components for combustion therein, with at least some of the gases being “cracked” to alter their molecular structure for further combustion to power the second turbine. The second turbine drives a compressor to supply air to the reactor. At least one of the ITMs precludes atmospheric nitrogen from the combustion processes, with the resulting exhaust including pure water and carbon dioxide. The carbon dioxide is either recycled into the reactor to facilitate fuel atomization, or compressed for sequestration.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to power generating systems, andparticularly to a power turbine system utilizing oxy-combustion forcarbon capture.

2. Description of the Related Art

Increasing population pressures and the demand for increased comforthave resulted in increasing demands for power production. These demandshave generally been met conventionally by power plants burning fossilfuels, i.e., coal and various weights or viscosities of fuel oils. Theproblem with the use of such fuels in conventional power plants is thattheir exhaust emissions contain massive amounts of carbon dioxide (CO₂),which is known as a “greenhouse gas” that contributes substantially toglobal warming. Also, as gaseous nitrogen (N₂) forms about 80% of theearth's atmosphere, a certain amount of the atmospheric oxygen (O₂) usedin the combustion of fossil fuels instead combines with some of theatmospheric nitrogen due to the heat developed during the combustionprocess, producing various oxides of nitrogen (NOx) that are harmful tothe atmosphere.

While certain other energy sources have been developed for theproduction of power, e.g., hydroelectric, solar, etc., these “clean”energy sources have not been able to keep up with the increasing demandsfor power in most areas of the world. Accordingly, it is necessary tocontinue to burn fossil fuels to respond to power demands throughoutmost of the world, with the resulting CO₂ and NOx emissions beingaccepted as a necessary evil of such power production. While manyadvances have been made in the reduction of CO₂ and NOx emissions frompower plants and other sources, emissions from fossil fuel burning powerplants are by no means perfectly clean in this regard.

Thus, a power turbine system solving the aforementioned problems isdesired.

SUMMARY OF THE INVENTION

The power turbine system essentially comprises two power turbines incommunication with an ion transport membrane (ITM) reactor that combustsfuel to provide energy to the turbines. The ITM reactor includes aseries of concentric cylindrical ion transport membranes that definecorresponding working chambers, and a centrally disposed “button cell”or disc-shaped ion transport membrane. Heavy liquid fuel is injected orpumped into the reactor, and is burned in a two-stage process to promotemore complete combustion with fewer undesirable exhaust byproducts.Atmospheric air is pumped into the reactor from the second turbine,which is dedicated to driving a compressor to supply air to the reactor.Some of the ITMs within the reactor serve to separate atmospheric oxygen(O₂) from the air, with the oxygen passing through the membranes forcombustion with the fuel. Atmospheric nitrogen (N₂) is restricted fromthe combustion process, and is ultimately exhausted from the reactor.The exhaust resulting from combustion is essentially pure water (H₂O)and carbon dioxide (CO₂), with some of the CO₂ being recycled into thereactor at the fuel injector to assist in “cracking” the heavy liquidfuel into extremely fine droplets to optimize combustion. The remainingbalance of the CO₂ is collected for sequestration.

The ITM reactor also produces a synthetic gas (“syngas”) of gaseoushydrogen (H₂) and carbon monoxide (CO) that is combusted with gaseousoxygen (O₂), with the resulting combustion product (CO₂ and H₂O) drivingthe second turbine. The result of the various combustive processes andreactions within the ITM reactor is the production of useful power fromthe output of the first turbine, with the exhaust products comprisingessentially pure water, carbon dioxide that is sequestered to preventrelease to the atmosphere, and free gaseous nitrogen that is releasedback to the atmosphere.

These and other features of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The sole drawing FIGURE is a schematic side view in section of a powerturbine system according to the present invention, illustrating itsgeneral features.

Similar reference characters denote corresponding features consistentlythroughout the attached drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The power turbine system incorporates two separate power turbines thatreceive their input energy from an ion transport membrane (ITM) reactor,rather than from a conventional combustion source. For example, theturbines of the ITM reactor can be powered by oxy-combustion of a heavyliquid fuel in the ITM reactor.

The ITM reactor utilizes a series of ion transport membranes (ITMs)within the reactor that separate oxygen from other atmospheric andexhaust gases in the reactor, resulting in a final exhaust productcomprising essentially pure carbon dioxide (CO₂) that is recycled orsequestered, and water. Thus, oxygen is separated inside the combustionsystem using the ion transport membranes (ITMs). Suitable membranematerials which can be used include, for example, lanthanum cobaltiteperovskite ceramics, modified proviskite ceramics, brownmilleritestructured ceramics, ceramic metal dual phase membranes, in addition to,thin duel phase membranes which includes chemically stableyttria-stabilized zirconia (YSZ).

For oxy-combustion to occur, the hydrocarbon fuel, e.g., heavy liquidfuel, can be burned in a medium of pure oxygen and some recycled exhaustgases instead of air (nitrogen is not introduced into the combustionchamber). Oxygen is separated inside the ITM reactor using the iontransport membranes (ITM), typically at temperatures ranging from 650°C. to 950° C. The ion transport membranes (ITMs) are activated foroxygen separation from the feed side to the permeate side of themembrane. In the permeate side of the membrane, fuel is being burnedwith the separated oxygen in a medium of recycled carbon dioxide. Inthis process, the combustion products consist of a mixture of onlycarbon dioxide and water vapor. Water vapor can be easily condensed andaccordingly carbon dioxide can be captured for industrial use orstorage.

The drawing FIGURE provides a schematic elevation view in section of thepower turbine system 10. The multi-stage ITM reactor 12 can have acylindrical configuration, with a series of concentric cylindrical iontransport membranes (ITMs) defining a corresponding series of concentriccylindrical working chambers therebetween. A description of the variouscomponents of the power turbine system 10, depicted in the FIGURE, isprovided below.

A fuel pump 14 can pump a heavy liquid fuel, e.g., fuel oil, etc.,through a water and carbon dioxide heat exchanger or condenser 16disposed externally to the reactor 12. The condenser 16 serves to coolexhaust output (particularly the water vapor fraction) from the reactor12 while simultaneously warming the incoming heavy liquid fuel. Theheavy liquid fuel is indicated schematically in the drawing FIGURE by asingle arrow barb followed by a solid arrow head. The fuel can beinjected into the ITM reactor 12 by an injector 18 disposed at thebottom of the reactor. The fuel is injected into an elongate fuelevaporation core 20 (also designated by the letter A) disposed centrallywithin the reactor 12. A cylindrical fuel partial conversion chamber 26is disposed concentrically about the fuel evaporation core 20. Theinjected fuel is heated in the fuel evaporation core 20 by heat flowingfrom the cylindrical fuel partial conversion chamber 26, as described inmore detail below, which results in fuel evaporation. Atmospheric air,designated schematically in the drawing as arrows with single barbedarrowheads, is pumped into a first or central air delivery passage 22disposed concentrically above the fuel evaporation core 20. A centrallydisposed “button cell,” i.e., disc-shaped, ion transport membrane 24 islocated between the first air delivery passage 22 and the fuelevaporation core 20. The button cell ion transport membrane 24 permitsonly oxygen (O₂) to permeate therethrough. The remaining oxygen depletedair (nitrogen and other trace gas) leaves the reactor through a gaseousnitrogen output chamber 28. Partial combustion or conversion of thevaporized fuel, indicated by arrows having three barbed heads, can occurclose to the surface of the button cell ITM 24 in the fuel partialconversion chamber 26 (also designated by the letter B in the drawingFIGURE) due to the oxygen passing through the button cell ITM 24. Theresulting heat is used in heating and evaporating the liquid fuelintroduced into the fuel evaporation core 20 to activate it for oxygenpermeation.

The button cell ITM 24 extends diametrically above the fuel partialconversion chamber 26 to provide oxygen to the fuel within the fuelpartial conversion chamber 26, and thereby, provide partially convertedor burned fuel. The partial fuel conversion chamber 26 also serves as aheavy liquid fuel heater, as some of the heat developed by thecombustion process within the fuel partial conversion chamber 26 istransferred to the central fuel evaporation core 20 to assist in thefuel evaporation process. Oxygen-depleted air comprising nearly purenitrogen (N₂, represented by arrows with single barb heads) is blockedby the button cell ITM 24, and flows upward through the gaseous nitrogenoutput chamber 28 (also designated by the letter H) disposedconcentrically about the first air delivery passage 22 and above thefuel partial conversion chamber 26, and thence out of the reactor 12 tothe atmosphere.

The partially converted or burned fuel flows from a lower portion of thefuel partial conversion chamber 26 into a cylindrical fuel completeconversion chamber 30 (also designated by the letter C) disposedconcentrically about the fuel partial conversion chamber 26 and thegaseous nitrogen output chamber 28. The outer wall of this chamber 30 isdefined by a cylindrical first oxygen separation membrane 32 (an ITM)disposed concentrically about the fuel complete conversion chamber 30.Atmospheric air (represented by arrows with single barb heads) is pumpedinto a cylindrical second air delivery passage 34 disposed about thefirst oxygen separation membrane 32, with oxygen passing through thefirst oxygen separation membrane 32 and into the fuel completeconversion chamber 30, where the fuel is completely converted orcombusted to form a first exhaust product. Heat resulting from thecombustion process in the fuel complete conversion chamber 30 serves toheat the first oxygen separation membrane (ITM) 32 for greaterefficiency, with some of this heat being transferred to the incomingatmospheric air flowing through the second air delivery passage 34.Excess oxygen depleted air 36 (nearly all gaseous nitrogen, N₂) flowsfrom the second air delivery passage 34, out the bottom of the reactor12.

The first exhaust product is formed in the fuel complete conversionchamber 30 by the combustion of the heavy fuel, comprising varioushydrocarbon forms, with essentially pure oxygen, as described above. Theresulting first exhaust product includes essentially pure carbon dioxide(CO₂) and water (H₂O), as there is no nitrogen involved in thecombustion process to form various oxides of nitrogen (NOx). The carbondioxide and water first exhaust product departs the top of the fuelcomplete conversion chamber 30 and flows to a first power turbine 38 todrive the turbine, which produces useful work by means of its outputshaft 40.

Rather than expelling the carbon dioxide and water first exhaust productto the atmosphere, this first exhaust product is recycled back to thereactor 12 where it flows into a first turbine exhaust collection andsynthetic gas production chamber 42 (also designated by the letter F)disposed concentrically about an outermost or third oxygen separationmembrane 44. This flow is indicated by arrows with two barbed heads inthe drawing FIGURE. As this first exhaust product reaches the lower endof the chamber 42, it flows radially inward to flow into and upward intoa concentric cylindrical synthetic gas (syngas) combustion chamber 46disposed between concentric cylindrical second and third oxygenseparation membranes, respectively 48 and 44, disposed respectivelyabout the second air delivery passage 34 and the synthetic gascombustion chamber 46.

It should be noted that the gases at the lower or outflow end of thefirst turbine exhaust and syngas production chamber 42 include carbonmonoxide (CO) and gaseous hydrogen (H₂), i.e., “syngas.” This is becausesome of the oxygen bound in the carbon dioxide (CO₂) and water (H₂O)molecules is stripped from its molecules during the passage of the firstturbine exhaust through the chamber 42. However, the second and thirdITM oxygen separation membranes 48 and 44 defining the syngas combustionchamber 46 concentrically therebetween, provide oxygen to complete theoxidation process (combustion) of the carbon monoxide and gaseoushydrogen within the syngas combustion chamber 46, resulting inessentially pure carbon dioxide (CO₂) and water (H₂O) for a secondexhaust product, indicated by the solid head arrows within the syngascombustion chamber 46.

The second exhaust product flows from the synthetic gas combustionchamber 46 to power a second power turbine 50. This second power turbine50 functions primarily to drive an air compressor 52, which draws inatmospheric air 54 and compresses that air to deliver it to the two airdelivery passages 22 and 34. The second power turbine 50 may alsoprovide useful mechanical power by means of an output shaft 56.

Exhaust gases from the second power turbine comprise essentially purecarbon dioxide (CO₂) and water (H₂O), with these gases being returned tothe outermost second turbine exhaust collection chamber 58 (alsoindicated by the letter G), disposed concentrically about the firstturbine exhaust collection and synthetic gas production chamber 42.These second power turbine exhaust gases are represented by arrowshaving four barbed heads. The placement of the second turbine exhaustcollection chamber 58 about the other chambers of the reactor 12 servesto heat the other chambers, which is desirable in order to optimize theefficiency of the various ion transport membranes 24, 32, 44, and 48within the reactor 12.

The second turbine exhaust gases are collected and routed to the heatexchanger and condenser 16, where they warm the incoming heavy liquidfuel to assist in its evaporation. The incoming heavy liquid fuel alsocools the exhaust gases, particularly the water vapor therein, withliquid water flowing from the heat exchanger and condenser 16 forcollection. The carbon dioxide portion of the exhaust is also collectedfor sequestration, with a portion of that carbon dioxide exhaust beingrecirculated to the heavy liquid fuel prior to its injection into thefuel evaporation core 20. The recirculated CO₂ assists in atomizing theheavy liquid fuel and carrying the atomized and/or evaporated fuelthrough the fuel evaporation core 20 and further through the fuelpartial conversion chamber 26 and fuel complete combustion chamber 30.

It will be noted that gas flow through the various chambers of thereactor 12 is configured such that the flow in each chamber, asindicated by the direction of the various gas flow arrows, is in theopposite direction to that of the adjacent chambers, with the exceptionof the outermost second turbine exhaust collection chamber 58. Thiscounter-current flow between adjacent chambers serves to increase theoxygen permeation rate of the various ITMs of the system. This flowconfiguration results in the low oxygen partial pressure region on oneside of a given ITM corresponding with the partial pressure region, andvice versa. The net result of this opposite flow direction orcounter-current is a more uniform and stable flame distribution andcorrespondingly more uniform membrane surface temperature, thusenhancing ITM life within the reactor 12.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

We claim:
 1. A power turbine system, comprising: a multi-stage iontransport membrane reactor, the multi-stage ion transport membranereactor having a plurality of mutually concentric cylindrical iontransport membranes therein, the membranes defining correspondingworking chambers therebetween, and a centrally disposed button cell iontransport membrane; at least one power turbine communicating with thereactor; an elongate fuel evaporation core disposed centrally within thereactor; a first air delivery passage disposed above the fuelevaporation core, the button cell ion transport membrane disposedbetween the fuel evaporation core and the first air delivery passage; acylindrical fuel partial conversion chamber disposed concentricallyabout the fuel evaporation core; a gaseous nitrogen output chamberdisposed concentrically about the first air delivery passage; acylindrical fuel complete conversion chamber disposed concentricallyabout the fuel partial conversion chamber and the gaseous nitrogenoutput chamber; a cylindrical first oxygen separation membrane disposedconcentrically about the fuel complete conversion chamber; a cylindricalsecond air delivery passage disposed about the first oxygen separationmembrane; a cylindrical second oxygen separation membrane disposedconcentrically about the second air delivery passage; a synthetic gascombustion chamber disposed concentrically about the second oxygenseparation membrane; a cylindrical third oxygen separation membranedisposed concentrically about the synthetic gas combustion chamber; afirst turbine exhaust collection and synthetic gas production chamberdisposed concentrically about the third oxygen separation membrane; anda cylindrical second turbine exhaust collection chamber disposedconcentrically about the first turbine exhaust collection chamber. 2.The power turbine system according to claim 1, further comprising: afirst power turbine communicating with the reactor, the first powerturbine being driven by a first exhaust product produced by combustionof a heavy liquid fuel within the reactor, the first exhaust productincluding carbon dioxide (CO₂) and water (H₂O); a second power turbinecommunicating with the reactor, the second power turbine being driven bya second exhaust product comprising a synthetic gas produced within thereactor, the second exhaust product including carbon dioxide (CO₂) andwater (H₂O); and an air compressor communicating with the second powerturbine and the reactor, the second power turbine driving the aircompressor, the air compressor delivering air to the reactor.
 3. Thepower turbine system according to claim 1, further comprising: a heavyliquid fuel heater disposed within the reactor, the reactor combusting aheavy liquid fuel therein to produce at least one exhaust product, aportion of the at least one exhaust product comprising carbon dioxide;and a water and carbon dioxide condenser and collector disposedexternally to the reactor, the condenser and collector communicatingwith the reactor, the condenser and collector recycling a first portionof collected carbon dioxide back to the reactor and further delivering asecond portion of collected carbon dioxide for sequestration.
 4. Thepower turbine system according to claim 1, wherein the first turbineexhaust collection and synthetic gas production chamber communicateswith the first turbine and the second turbine exhaust collection chambercommunicates with the second turbine.
 5. The power turbine systemaccording to claim 1, wherein the first oxygen separation membrane, thesecond oxygen separation membrane, and the third oxygen separationmembrane include ion transport membranes.
 6. The power turbine systemaccording to claim 1, wherein: the fuel partial conversion chamber isadapted for partial combustion of fuel therein; and the fuel completeconversion chamber communicates with the fuel partial conversionchamber, the fuel complete conversion chamber being adapted for completecombustion of fuel therein.
 7. A power turbine system, comprising: amulti-stage ion transport membrane reactor, the multi-stage iontransport membrane reactor having an elongate fuel evaporation core, afirst air delivery passage disposed above the fuel evaporation core, abutton cell ion transport membrane disposed between the fuel evaporationcore and the first air delivery passage, and a plurality of iontransport membranes spaced from the elongate fuel evaporation core andthe first air delivery passage, the membranes defining correspondingworking chambers therebetween; a first power turbine communicating withthe reactor; a second power turbine communicating with the reactor; anair compressor communicating with the second power turbine and thereactor; a cylindrical fuel partial conversion chamber disposedconcentrically about the fuel evaporation core; a gaseous nitrogenoutput chamber disposed concentrically about the first air deliverypassage; a cylindrical fuel complete conversion chamber disposedconcentrically about the fuel partial conversion chamber and the gaseousnitrogen output chamber; a cylindrical first oxygen separation membranedisposed concentrically about the fuel complete conversion chamber; acylindrical second air delivery passage disposed about the first oxygenseparation membrane; a cylindrical second oxygen separation membranedisposed concentrically about the second air delivery passage; asynthetic gas combustion chamber disposed concentrically about thesecond oxygen separation membrane; a cylindrical third oxygen separationmembrane disposed concentrically about the synthetic gas combustionchamber; a first turbine exhaust collection and synthetic gas productionchamber disposed concentrically about the third oxygen separationmembrane; and a cylindrical second turbine exhaust collection chamberdisposed concentrically about the first turbine exhaust collectionchamber.
 8. The power turbine system according to claim 7, wherein theion transport membranes are disposed in a mutually concentriccylindrical array.
 9. The power turbine system according to claim 7,further comprising: a heavy liquid fuel heater disposed within thereactor, the reactor combusting a heavy liquid fuel therein to produceat least one exhaust product, a portion of the at least one exhaustproduct comprising carbon dioxide; and a water and carbon dioxidecondenser and collector disposed externally to the reactor, thecondenser and collector communicating with the reactor, the condenserand collector recycling a first portion of collected carbon dioxide backto the reactor and further delivering a second portion of collectedcarbon dioxide for sequestration.
 10. The power turbine system accordingto claim 7, wherein the first turbine exhaust collection and syntheticgas production chamber communicates with the first turbine and thesecond turbine exhaust collection chamber communicates with the secondturbine.
 11. The power turbine system according to claim 7, wherein thefirst oxygen separation membrane, the second oxygen separation membrane,and the third oxygen separation membrane include ion transportmembranes.
 12. The power turbine system according to claim 7, wherein:the fuel partial conversion chamber is adapted for partial combustion offuel therein; and the fuel complete conversion chamber communicates withthe fuel partial conversion chamber, the fuel complete conversionchamber being adapted for complete combustion of fuel therein.
 13. Amethod for liquid fuel combustion using the multi-stage ion transportmembrane reactor according to claim 7, comprising the steps of:introducing liquid fuel into the elongate fuel evaporation core;introducing compressed atmospheric air into the first air deliverypassage; separating oxygen from the compressed atmospheric air throughthe button cell ion transport membrane; introducing the oxygen into thefuel partial conversion chamber through the button cell ion transportmembrane; partially converting fuel flowing in the partial conversionchamber using the oxygen flowing from the button cell ion transportmembrane to provide partially converted fuel; flowing the partiallyconverted fuel into the fuel complete conversion chamber; introducingcompressed atmospheric air into the second air delivery passage; passingoxygen from the atmospheric air in the second air delivery passagethrough the first oxygen separation membrane into the fuel completeconversion chamber for complete combustion of fuel flowing therein toprovide a first exhaust product comprising carbon dioxide (CO₂) andwater (H₂O); powering the first turbine with the first exhaust product;flowing the first exhaust product from the first turbine through thefirst turbine exhaust collection and synthetic gas production chamber tothe synthetic gas combustion chamber; receiving oxygen in the syntheticgas combustion chamber through the second and third oxygen separationmembranes to completely combust the first exhaust product in thesynthetic gas combustion chamber and produce a second exhaust product;and driving the second power turbine with the second exhaust product.14. The method for liquid fuel combustion using the multi-stage iontransport membrane reactor according to claim 13, further comprising:flowing the second exhaust product from the second power turbine throughthe second turbine exhaust collection chamber to a heat exchanger andcondenser.
 15. The method for liquid fuel combustion using themulti-stage ion transport membrane reactor according to claim 13,wherein flow in the fuel partial conversion chamber, the gaseousnitrogen output chamber, the fuel complete conversion chamber, thesecond air delivery passage, the synthetic gas combustion chamber, andthe first turbine exhaust collection and synthetic gas productionchamber is in alternatingly opposite directions.